Molecular Dynamics Simulations of Turbostratic Dry and Hydrated Montmorillonite with Intercalated Carbon Dioxide

TL;DR

This study uses molecular dynamics simulations to explore the structural and energetic effects of rotational disorder and CO2 intercalation in hydrated and dry montmorillonite, relevant for geological carbon storage.

Contribution

It provides new insights into the energetic costs and structural changes associated with turbostratic stacking and CO2 intercalation in montmorillonite clay minerals.

Findings

Turbostratic stacking increases interlayer spacing and is energetically demanding.

Rotational disordering in dry systems can be energetically favorable.

Interlayer species distributions depend on rotational angles.

Abstract

Molecular dynamics simulations using classical force fields were carried out to study energetic and structural properties of rotationally disordered clay mineral-water-CO2 systems at pressure and temperature relevant to geological carbon storage. The simulations show that turbostratic stacking of hydrated Na- and Ca-montmorillonite and hydrated montmorillonite with intercalated carbon dioxide is an energetically demanding process accompanied by an increase in the interlayer spacing. On the other hand, rotational disordering of dry or nearly dry smectite systems can be energetically favorable. The distributions of interlayer species are calculated as a function of the rotational angle between adjacent clay layers.